ntp: fix non privileged system time shifting

The ADJ_SETOFFSET bit added in commit 094aa18 ("ntp: Add ADJ_SETOFFSET mode bit") also introduced a way for any user to change the system time. Sneaky or buggy calls to adjtimex() could set ADJ_OFFSET_SS_READ | ADJ_SETOFFSET which would result in a successful call to timekeeping_inject_offset(). This patch fixes the issue by adding the capability check. Signed-off-by: Richard Cochran <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
liveeasily · Apr 4, 2011 · 4352d9d · 4352d9d
1 parent b3b896c
commit 4352d9d
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
@@ -652,6 +652,8 @@ int do_adjtimex(struct timex *txc)
 		struct timespec delta;
 		delta.tv_sec  = txc->time.tv_sec;
 		delta.tv_nsec = txc->time.tv_usec;
+		if (!capable(CAP_SYS_TIME))
+			return -EPERM;
 		if (!(txc->modes & ADJ_NANO))
 			delta.tv_nsec *= 1000;
 		result = timekeeping_inject_offset(&delta);